Not exactly software, but I dumped the Brewers Association Beer Style Guidelines (just updated (mostly) to the 2006 version) into mysql, and wrote a little search wrapper for it:
My goal was this: I brew a lot of 'random' beers, and am often not sure of the styles they might be classified as. Searching through the guides can be tough ... so I thought this would be easier, and more fun.
I got the styles here:
Take a look and let me know what you think!
DISCLAIMER: I'm not much of a programmer. If you see anything I might do better or different, let me know! I'm not proud.